function rad(d) {
	return d * Math.PI / 180.0;
}


// 根据经纬度计算距离，参数分别为第一点的纬度，经度；第二点的纬度，经度
function getDistance(lat1, lng1, lat2, lng2) {
	var radLat1 = rad(lat1);
	var radLat2 = rad(lat2);
	var a = radLat1 - radLat2;
	var b = rad(lng1) - rad(lng2);
	var s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2) +
		Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));
	s = s * 6378.137; // EARTH_RADIUS;
	s = Math.round(s * 10000) / 10000; //输出为公里

	var distance = s;
	var distance_str = "";

	if (parseInt(distance) >= 1) {
		distance_str = distance + "km";
	} else {
		distance_str = Math.floor(distance * 1000) + "m";
	}

	//s=s.toFixed(4);

	// console.info('lyj 距离是', s);
	// console.info('lyj 距离是', distance_str);
	return distance_str;
}

export default getDistance